davey



E. N. DAVEY.

TOOL HOLDER. v APPLICATION FILED MAR-11.1918.

1,319,950. Patented 001;. 28,1919.

FIG. 2

f /9 5 go l i I I I ERNEST N. DAVEY, OF LACI-IINE, QUEBEC, CANADA.

TOOL-HOLDER.

Specification of Letters Patent.

Patented Oct. 28, 1919.

Application filed. March 11, 1918. Serial No. 221,725.

To all whom it may concern:

Be it known that I, ERNEST N. DAVEY, a subject of the King of Great Britain, and resident of the city of Lachine, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Tool-Holders, of which the following is a full, clear, and exact description.

This invention relates to improvements in tool holders, and the object of the invention is to provide a simple, durable and inexpensive holder for the high speed steel tools at present in general use.

A further object is to provide a one-piece holder which is automatic in its action in gripping the tool.

A still further object is to provide a holder in which the grip on the tool is at the very extremity of the holder, so that very short tools may be used.

Still another object is to provide a holder which will completely overcome any tend ency to chattering, so that the tool may be used in the place of ordinary tool holders and in the place of the spring holders used in certain special cases.

The universal employment of expensive, high speed, steel tools has led to the adoption of holders with a view to reducing to a minimum the amount of expensive steel used and also to permit the use of short lengths. These holders are for the most part drop forgings and the tool is secured in the holder by means of a set screw or cam. Such arrangements have numerous disadvantages and all machine shops have on hand a considerable number of holders, which have been rendered useless by reason of the set screw heads being twisted off in clamping the tool in place. It will frequently happen that a tool holder will thus be rendered useless before it is ever put to use. The breakage may be caused by carelessness of the workmen or may be due to faulty construction of the tool recess or to a tool warped in the tempering. In addition to this, such holders have certain inherent disadvantages. They are bulky or have projections close to the tool point, so that it is frequently diflicult to watch the point of the tool and in some cases difiicult to get the tool up to its work without setting it so far out of the holder that the full cutting capacity of the tool is not available for fear of breaking it. Another very great inherent disadvantage is that the tool is supported from above at only one point, which is a considerable distance back from the end of the holder and from the point of the tool. Pressure of the clamping means tends to spring up the ends of the tool, so that the tool between its point and the clamping means is not supported from below and chattering re-' sults. Frequently, tools are slightly warped in tempering and the same result produced. When certain classes of work are undertaken, it is necessary to change from these rigid holders to special spring holders. Another disadvantage of the present day tool holders is that, owing to the presence of tool clam-ping elements, the shape of the holder cannot be altered at will to adapt it to special work, so that specially constructed holders are often required. Furthermore, owing to the nature of the material used and the stress which is transmitted from top to bottom of the holder through the sides, it is necessary to make the holder of considerable thickness. Careless workmen frequently lose the tools out of holders between the tool room and machine, and much time is lost in finding the tool or in grinding a new one.

In order to overcome these disadvantages, I have devised a tool holder consisting of a single piece, which will grip the tool more securely than heretofore possible, and will furthermore grip the tool at the very extremity of the holder, so that chattering will be overcome. Various other features and advantages of the holder will be ascertained hereinafter.

The invention consists briefly in providing a holder having a pair of parallel resilient arms, each recessed to receive a portion of the tool and designed to grip the tool at their free extremities.

In the drawings which illustrate the invention;

Figure 1 is a side elevation of a straight holder as it appears in use carrying a tool and mounted in a tool post.

Fig. 2 is a plan view of an offset holder.

Fig. 3 is a side elevation of an offset holder.

Fig. 4 is an end elevation showing a modification which may be applied to either straight or offset holders.

Fig. 5 isa longitudinal section of a bar finished ready for bending into form.

Referring more particularly to the drawof upper and lower parallel arms 15 and 16 respectively, which are rigidly connected together at one end, as at 17, and suitably tapered at the opposite and free ends, as at For a short distance from their connected ends, the arms, are in contact, as at 19, but for the remainder of their length they are separated, leaving a space 20 be tween them which will permit the arms to be flexed or pressed together at their free extremities. One of the arms (which in the drawings is shown to be the upper arm 15) is provided with a groove or recess 21, extending from the free end to the contacting portions 19 of the arms and increasing in depth from the free extremity toward the connected extremities. The other arm is provided with a similar groove 0r recess 22, which is preferably though not necessarily parallel with the upper and lower surfaces of the arm. These grooves or recesses are each designed to receive a portion of the tool 23. It will be clearly seen from Fig. 1 that owing to the taper of the recess 21, the tool will be gri ped at the free extremity of the arm 18. t is intended that the tool shall be a snug sliding fit between the extremities of the arms, so that it will not with ordinary handling slip out of the holder. In a holder of the straight type, as shown in Fig. 1, a small passage 23 may be provided through the closed end of the holder communicating with the passage formed by the grooves or recesses 21 and 22, through which a wire or other instrument may be introduced to expel a tool which has been forced too far into the holder to be gripped and pulled out. The offset type of holder shown in Figs. 2 and 3 has exactly the same characteristics of construction as the straight holder just described, with the exception that the grooves 21 and 22 naturally follow the line of the inclined nose portion 24, and therefore run out at the side of the holder instead of continuing the full length of the space 20. Fig. 1 illustrates the substitution of recesses or raibbets 25 and 26 open at one side of the holder instead of grooves, such as shown in Fig. 3. In other respects the characteristics of construction are exactly as before described.

The main feature of the holder is that it is a strictly one-piece article; the two arms being for all practical purposes integral. It is immaterial whether the arms are made from a single piece of metal bentupon itself, as shown in Fig. 1, or from two pieces secured together, as shown in Fig. 3. When the holder is made of two pieces of metal, they may be secured together by rivets 27,

as shown, or may be welded together or both. It will also be understood that a holder made of a single piece of metal, as shown in Fig. 1, may in addition have the arms welded together through the whole or part of the length of their contacting surfaces 19. It will also be understood that the arrangement of grooves or recesses illustrated may be reversed or that both grooves or recesses may be parallel with the arms, or may both be tapered without departing from the spirit of of the invention. It will also be understood that mechanical equivalents of the tapered groove, such as the provision of a groove shouldered close to the nose of the holder to localize the grip of the tool, are considered as within the scope of the invention. While the holder has heretofore been described as comprising two arms rigidly connected at one end, it will be obvious that the two arms may be hingedly connected with the sacrifice of only two features, namely, the one-piece construction and the retention of the tool when the holder is not in the tool post.

The holder, whether of the one-piece or two-piece type, may be quickly and easily manufactured by milling away a portion of one arm, so as to form the space 20, and then milling the grooves. The arms are then assembled into operative position either by bending the metal, as in Fig. 1, or securing the two arms together as in Fig. 3. It will be understood that if desired the form shown in Fig. 1 may be strengthened by the addition of a rivet.

The operation of the holder is extremely simple. A tool having been ground to proper shape is inserted in the holder by forcing the arms slightly apart. The resiliency of the metal in the arms then causes the tool to be firmly gripped, so that it will not fall out of the holder but may yet be adjusted in or out, as desired. The holder is now placed in the tool post of a lathe and the clamping screw tightened. The grip of the holder on the tool is in any case at the extreme point or nose of the holder and, therefore, as close to the point of the tool as possible. When the clamping screw is tightened, it tends to flex the upper arm 15, thus increasing the grip on the tool at the extremity of the holder, and also to increase the contacting surface of the holder and tool by bringing additional surface of the tapered groove into contact with the tool. The same action occurs in the offset holder as in the straight holder and also in a holder constructed, as shown in Fig. 4:. Owing to the grip of the holder being at the very extremity of the nose, very much shorter tools may be used' than is possible with the ordinary holders where the set screw or cam may be an inch or more back from the end of the. holder. The advantages of this holder will be obvious to those skilled in shop practice and may therefore be very briefly enumerated. The holder may be more easily and cheaply manufactured than the ordinary holders, as it is a simple proposition of machining steel bars and no drop forgings are required. The holder is a strictly one-piece article and there are therefore no parts to be lost or broken. The holder automatically grips the tool from the moment it is inserted and loss of tools between tool room and machine is therefore prevented. No special operation is required to secure the tool in the holder, as this is automatically done when the holder is clamped in the tool post, and no additional tightening of the clamping screw is required beyond that necessary to secure the holder against movement. The holder has no projecting parts which interfere with the users line of vision to the tool point or which may interfere with getting the tool into intricate work. The holder is much smaller in proportion to the size of the tool than the holders at present in use and the tool may therefore be brought to its cutting position more easily. There being no set screws or additional parts to secure the tool, it becomes possible to grind the nose of the holder to any shape required for special work. Offset holders made according to this invention may be used either right or left hand, which is not possible with the ordinary holders. For very light work or where an extremely cheap holder is desired, it may be a malleable or an ordinary casting.

Having thus described my invention, what I claim is 1. A tool holder comprising a bar of .metal having its upper and lower surfaces parallel, sa1d bar be1ng cut away at one end of its upper surface parallel with the surface and grooved in said cut away portion, the bottom of said groove being parallel with the cut away surface and the said bar being also grooved at its opposite end,

said groove deepening from the end toward the center of the bar, said bar being folded upon itself, whereby the edges of said grooved portionslie in parallelism and spaced relation and the bottoms of the grooves out of parallel.

2. A tool holder comprising a pair of parallel arms connected at one end and arranged in spaced relation and grooved upon ad acent surfaces, one of said grooves increaslng in depth from the free end of the arms.

8. A tool holder comprising a pair 015.50

resilient arms rigidly connected together at one end and separated at the opposite end,

and having tool gripping surfaces closer together at the free extremities of the arms! than at any other point.

ing toward the free ends of the arms.

5. A tool holder comprising a pair of arms connected together at one end and free at the opposite end, said arms having tool gripping surfaces closer together at the free ends of the arms than toward the connected ends.

6. A tool holder comprising a pair of resilient arms rigidly connected together at one end and spaced apart at the opposite end, and tool receiving recesses in adjacent surfaces of said arms, the bottoms of the recesses converging toward the free extremities of the arms.

7. A tool holder comprising a pair of parallel resilient arms rigidly connected together at one end and spaced apart at the opposite end, and tool receiving recesses in adjacent surfaces of said arms, the bottoms of the recesses being closer together at the free extremities of the arms.

In witness whereof, I have hereunto set my hand.

ERNEST N. DAVEY.

Copies 01. this patent may be obtained. for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

